Conventionally, a mask-repairing method on the principle of the ion beam CVD method has been proposed. See, for example, Proc. 9th Symp. on ISIAT 786, P657-664.
A process for forming a pattern film comprises irradiating a specific portion of a substrate on which a pattern film is to be formed with a focused ion beam, and spraying directly a vapor stream of a polymerizable or carbonizable organic compound at and around the area being irradiated with the focused ion beam to thereby polymerize or carbonize the organic compound at said specific portion to form a desired pattern film thereon. Also it is possible to form an electric conductive film by using a vapor of metalizable compound in the above method.
The conventional methods have various problems as described below.
The white-spot defects in the patterned film mask appear to be completely repaired by the above-mentioned conventional technique, insofar as judged from the standpoint of light-transmitting observation and the mask defects inspection. However, by copying the mask pattern by means of an exposure device, it becomes clear that at the sides of the repaired portion where an opaque film has been formed, film fringes are made according to the exposure condition. Therefore, the exposure condition is restricted. To explain this in detail, as a result of inspection by means of reflected light, analysis of the secondary ion mass and the like, it can be shown that an extremely thin (several tens .ANG.) film fringe (which has the same quality as that of the light shielding film formed for repairing) is made at the sides of the repaired -portion (where an opaque film is formed). The film fringe reflects and absorbs light, so that the light-transmitting rate is a little lowered. Accordingly, this brings about the problem of the exposure condition. Similarly, when an electric-conductive pattern film is formed on a semiconductive device such as an IC, by the above conventional method, the film sometimes shows an electrical defect by the fringe of the film.